The invention relates to a vehicle occupant restraint system comprising at least one belt retractor comprising a frame, a belt reel rotatably mounted in the frame, a locking mechanism for selectively blocking the belt reel and a vehicle-sensitive sensor.
In addition to the usual belt webbing and/or vehicle-sensitive locking functions modern belt retractors may need to be equipped with additional functions where necessary. One of these additional functions is safeguarding loads or child seats by a blocking condition which is activated by total withdrawal and subsequent renewed retraction of the belt webbing. Switching back into the emergency locking condition is achieved by total retraction of the belt webbing. Another additional function is a buckled up indication for which the withdrawn belt webbing length is sensed.
Such additional functions of a belt retractor necessitate a high complexity of mechanical components. A particularly high amount of design labour is required to provide a variety of different belt retractor types for each of the additional functions required.
The invention provides an occupant restraint system which in the field of belt retractors enables a series of optional functions, relevant in terms of safety and comfort.
The belt retractor of the restraint system in accordance with the invention contains a frame, a belt reel rotatably mounted in the frame, a locking mechanism for selectively blocking the belt reel and a vehicle-sensitive sensor. For actuating the locking mechanism an actor is provided. The functions of the belt retractor are controlled by an electronic control unit including an input interface and an output interface. The vehicle-sensitive sensor is connected to the input interface and the actor is connected to the output interface. It is this basic design concept that facilitates adapting the locking and retraction functions of the belt retractor to the respective requirements, since merely program data need to be adapted, according to which the electronic control unit works. Furthermore, various sensors can be connected to the input interface of the electronic control unit, the output signals of which are taken into account in driving the locking mechanism. Likewise further actors or positioners and the like may be connected to the output interface of the electronic control unit, the functions of which are controlled depending on the sensor signals as polled via the input interface of the electronic control unit. The rotary drive of the belt reel, in particular a servomotor, can not only undertake the function of the retraction spring of the conventional mechanical belt retractor, but can also assure a pretensioning of the belt webbing in case of an imminent vehicle crash or a tensioning of the belt webbing in defined situations. In particular, the invention provides a vehicle occupant restraint system which comprises at least one belt retractor which has a frame, a belt reel rotatably mounted in the frame, a locking mechanism for selectively blocking the belt reel, an actor for actuating the locking mechanism and an electric rotary drive coupled to the belt reel. An electronic control unit has an input interface for sensor signals and an output interface having post-connected drivers for driving the actor and the electric rotary drive.
The sensor signals comprise:
occupant detection signals,
vehicle condition signals,
vehicle environment signals;
The sensor signals are combined in the electronic control unit according to a predetermined triggering scheme, for the output of driving signals at the output interface, by which signals:
the belt reel is selectively acted upon with a controlled torque for winding up of belt webbing;
the belt reel is selectively driven with a controlled torque for tensioning the belt webbing;
the belt reel is selectively driven with a maximum available torque for tightening the belt webbing;
the actor selectively actuates the locking mechanism.
One of the sensors connected to the input interface furnishes in the preferred embodiment an incremental signal representing the rotation of the belt reel, preferably in conjunction with a further signal indicating the sense of rotation. These signals are analyzed by the electronic control unit by up/down counting to determine the absolute angle of rotation of the belt reel and thus the length of the belt webbing withdrawn.
In this preferred embodiment the belt retractor offers the following functions, some of which may also be achieved only when required:
child seat/load safeguarding
buckled up detection
vehicle-sensitive blocking
retraction spring
comfort gearing
blocking or belt tensioning on non-locked back rest
belt webbing-sensitive blocking
belt webbing pretensioning
belt webbing tensioning.